This feature is experimental and not part of Unpoly's stable API.
It may be removed or changed without prior notice or deprecation.
Returns a CSS selector that matches the given element as good as possible.
This uses, in decreasing order of priority:
- The element's
- The element's ID
- The element's name
- The element's classes
- The element's tag names
String or Element or jQuery
The element for which to create a selector.